JPS61207910A - Attitude measuring instrument - Google Patents

Abstract

PURPOSE:To derive at a high speed the attitude information of an object body by using a straight line for connecting plural segments having a correlation, obtained from distance information related to the object body, as a straight line equation of an attitude of the object body. CONSTITUTION:A laser range finder 1 irradiates a laser beam to a measuring object body, and inputs its distance information as an x-y-z coordinate data. A segment cutting part 2 cuts segments for showing the object bodies (a), (b) and (c) from in line information by utilizing the continuity of the x-y-z coordinate data, or a threshold value, etc. for discriminating the object body and the background. A collection input part 3 compares information of the segment which has been derived at every scanning line, and its previous information, and derives a group (collection) of the segment detected from the same object body extending over between plural scanning lines. With regard to each collection of the segments which have been obtained in this way, a straight line generating part 4 derives its center-of-gravity coordinates, respectively, and an equation of a straight line for connecting these center-of-gravity coordinates is calculated, and outputted as information for showing the attitude of the object body, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention provides for easily and quickly obtaining posture information of a measurement object from distance information of the measurement object obtained using a light projection means such as a laser range finder. The present invention relates to a posture measuring device that can be obtained.

[Technical background of the invention and its problems]

Robots that perform tasks such as grasping and moving objects,
It is important to accurately grasp the orientation of the object to be grasped, that is, the orientation of the object. In particular, when a robot is used to pick up so-called bulk parts, it is very important to accurately grasp the orientation of each part.

Conventionally, it was not possible to accurately grasp (measure) the posture of such an object.
A laser range finder, which can directly obtain distance information of each part of the object as its coordinate information, is often used as a means for this purpose.

Conventionally, all the coordinate information forming the object is obtained using a laser range finder, and the posture information of the object is obtained from the correlation of these coordinate information. Therefore, an enormous amount of calculation processing is required to obtain posture information of an object from these coordinate information. For this reason, it has been difficult to obtain posture information of an object at high speed and understand its posture.

Moreover, as the orientation information of the object is handled volumetrically as a mass of coordinate information as described above, a large-capacity storage device is required to write this information, and data necessary for controlling the robot is extracted from this information. There were some problems, such as the processing required to do so was quite complicated.

[Purpose of the invention]

The present invention was made in consideration of these circumstances, and its purpose is to provide a practical method that can easily and quickly grasp the posture of an object and effectively utilize it for robot control, etc. The object of the present invention is to provide a posture measuring device that is easy to use.

[Summary of the invention]

The present invention uses a light projection means such as a laser range finder to sequentially obtain distance information regarding an object to be measured as line information at predetermined scanning intervals, and calculates a line segment indicating the object to be measured in each of the line information. Information is extracted, for example, as information on the length and position of each line segment, and the connection relationship between each scanning line of the information on these line segments is extracted, for example, as a set of line segments that are mutually related between each line. The posture of the object to be measured is determined as an equation expressing a straight line connecting each line segment of this set.

〔Effect of the invention〕

Thus, according to the present invention, while sequentially inputting distance information regarding a target object at predetermined scanning intervals, a line segment indicating the target object in the line information is determined, and from the correlation between each line of these line segments, A plurality of correlated line segments are treated as a set of line segments indicating the same target object, and the straight line connecting each line segment of this set of line segments represents the attitude of the target object as a linear equation, so the attitude of the target object is expressed as a straight line equation. Posture information can be obtained quickly. Moreover, each time new line information is input, the line segment information extracted from the line information is added to the set of already determined line segments, and the linear equation is sequentially corrected. It becomes possible to determine the posture with high accuracy.

In addition, since the posture of the target object is expressed as a linear equation, it is possible to describe the posture of the target object using a small-capacity storage device, and the posture information can be directly used for robot control, etc. A great practical effect can be achieved, such as:

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

1 are schematic configuration diagrams of the embodiment apparatus, FIGS. 2 and 3 are diagrams showing the processing concept thereof, and FIG. 4 is a diagram showing an example of the processing sequence in the embodiment apparatus.

In this embodiment, various industrial parts that often have cylindrical (cylindrical) shaped parts are exemplified as objects to be measured, and a case will be described using as an example a case where this is grasped by a robot.

The laser range finder 1 irradiates a laser beam onto an object to be measured and inputs distance information therefrom, for example, as x-y-z coordinate data of each part of the object to be measured. Here, a laser range finder 1 is used in which distance information about the object to be measured is input line by line while moving a laser line with a predetermined scanning width at predetermined scanning intervals. With this laser range finder 1, distance information of a plurality of objects a, b, and c is sequentially inputted one scanning line at a time, as shown in FIG. 2(a), for example. Note that a laser range finder 1 may be used in which the distance information of the object to be measured is sequentially input while scanning the laser beam with a predetermined scanning width and moving the scanning line at predetermined scanning intervals. In this case, the distance information of the object to be measured that is input sequentially may be processed in units of one scanning line at a time.

A line segment cutting unit 2 extracts line segments indicating target objects a, b, and c from among line information sequentially input for each scanning line using the laser range finder 1, and extracts line segments indicating target objects a, b, and c from line information sequentially input for each scanning line using the laser range finder 1.
, c using the continuity of x-y-z coordinate data indicating each part, or a threshold value for distinguishing the target object from the background. For example, as shown in FIG. 2(b), the line segment between target objects a and b on the scanning line (K-1) is hl.

As h2, object a of interest also in scanning line K.

The line segment of b is h3. h4 is extracted from each line information. And each line segment old, h2. The information of ~h4 is, for example, length information and position information in the scanning area (area shown in the frame in the figure) by the laser range finder 1, for example, output as X=yz coordinate data. There is.

The set importing unit 3 then compares the line segment information obtained for each scanning line with the line segment information obtained for the previous scanning line, and compares the line segment information obtained for each scanning line with the line segment information obtained for the previous scanning line. We are looking for a set of line segments detected from a target object.

Specifically, information on each line segment cut out for each scanning line is compared between each scanning line, and line segments with approximately the same position information and approximately the same length are extracted from the same object. It is determined that it is a detected line segment. In the example shown in FIG. 2, line segments old and h3 are grouped together as one set (set) belonging to target object a, and line segments h2 and h4 are grouped together as one set (set) belonging to target object a. It can be summarized.

In addition, when comparing line segment information between each scanning line, if there are several line segments whose information values are similar, for example, lh2+"Flh311h41, line segments that are close in distance are is selected as a set (one set).Alternatively, set determination processing is performed by using information on straight lines connecting each line segment, which will be described later, of a set of line segments that have already been found.Set importing unit 3 Each time line segment information for each scanning line is sequentially given line by line, as described above, the set of line segments extracted from that scanning line has already been obtained (a set of line segments related to the same target object). The line segment to which the determined line segment belongs is determined and added to the determined set.If the set to which the determined line segment belongs is not found, the line segment is added to the determined set. Assuming that the segment is related to a newly appearing target object, a new set of line segments is created based on this segment.

For each set of line segments obtained in this way, the straight line generation unit 4 obtains the barycenter (center) coordinates of each set of line segments from the information on the length and position of each line segment belonging to the set, and connects these barycenter coordinates. Calculating the equation of a straight line. For example, the second
As shown in Figure (C), an equation representing the straight line f1 connecting the barycentric coordinates of the line segments h2 and h3 is obtained, and similarly, the equation of the straight line f1 connecting the barycentric coordinates of the line segments h2 and h3 is obtained.
An equation representing a straight line t2 connecting each barycenter coordinate of h4 is obtained. The equations of these straight lines fl and f2 are output as information indicating the postures (inclinations) of the target objects a and b, respectively, and are also written in the control information memory of the robot.

By the way, as described above, the information on the line segments belonging to the set of line segments representing the target object increases sequentially as the laser range finder 1 scans the line of the target object. For this reason,
At the initial stage of posture measurement, the newly added line segment does not necessarily exist exactly on the straight line that the straight line generation unit 4 finds from the information on two line segments forming one set. In other words, the information on each line segment itself includes a certain error, and the equation of the straight line connecting the two line segments is calculated from the information on two line segments that are almost not far apart from each other in terms of distance between adjacent lines. The amount of error in the linear equation is relatively large. Therefore, straight line correction section 5
In this case, the previously calculated linear equation is corrected each time a new line segment is added to each set of line segments.

For example, as shown in FIG. 3, after calculating the equation of the straight line F1 connecting the centroid points of line segments H1 and H2, the above line segment 1-11.
)l When line segment H3 is added to the set of 2, line segment H1
, H3, calculate the equation of the direct filF2 that connects the centroid points of H3. And these straight lines F1. The average value of each coefficient of F2 is determined, and an equation of a straight line F3 is determined using each of these average values as a coefficient.

The equation of this straight line F3 is a new equation obtained by modifying the straight line F1, that is, the equation of the straight line that interconnects the line segments H1, H2°H3 of the set. Thereafter, in the next scanning line, when line segment H4 is added to the set of line segments H1, H2, and H3, the linear equation is similarly corrected.

In this way, the line segment information regarding the recognition target object is sequentially compiled into a set of line segments corresponding to each target object,
As shown in FIG. 2(d), the posture of each target object is determined as a straight line connecting the line segments belonging to the set. That is, in this example, the line segment old, ha, ha, h
A set of line segments including h1.9 is extracted as representing the target object a, and these line segments h1. ha, h6. The equation of the straight line f1 connecting h9 is output as information indicating the attitude of the target object a. Similarly, line segment h2. h4.
h5. The equation of the straight line f2 connecting h.ha is obtained as information indicating the posture of the target object, and the line segment h7. The equation of the straight line t3 connecting IO is output as information indicating the attitude of the target object C.

FIG. 4 shows an example of a control sequence for the above-mentioned attitude measurement process.

As shown in this control sequence example, @ is set in the control parameters in response to the input of distance image information line by line by the laser range finder 1, and while extracting the line segment above the scanning line, the line segment to which the line segment belongs is set. A set is determined, an equation of a straight line connecting line segments belonging to each set is calculated, and the equation of this straight line is sequentially corrected. . By shifting in this manner, each posture of the target object existing within the measurement target region can be determined as a linear equation.

As explained above, according to this device, the distance information of the object to be measured is input, the distance information is processed in units of scanning lines, and the information of the object included in the line information is extracted as line segment information. Then, the object to be measured is captured as a set of line segments from the connection relationship of the above line segments between multiple lines,
The posture of the object to be measured is measured as an equation of a straight line connecting line segments that bend to the set. Therefore, as the line scanning of the target object is performed, the posture information of the target object is obtained as the linear equation, and the linear equation is sequentially corrected using new line segment information, so that the posture information of the target object can be obtained at high speed. can be obtained. In other words, it is possible to quickly obtain general orientation information of the target object and to sequentially correct this information to obtain highly accurate orientation information. Moreover, the above-mentioned posture measurement can be performed by simple processing of grouping line segments, calculating the equation of a straight line connecting each line segment belonging to the group, and correcting the equation.

Furthermore, since the orientation of the target object is expressed as a straight line equation, the only information necessary to store this is the coefficient information of the straight line equation, making it possible to significantly reduce the required storage capacity. Furthermore, since posture information is expressed as a linear equation, the information can be used directly for robot control. Therefore, there are no problems such as the need to use large-sized memory or the long processing time required in the past, and great practical effects can be achieved.

Note that the present invention is not limited to the embodiments described above. In the embodiment, a cylindrical (cylindrical) part was the measurement target, but all parts having a so-called elongated partial shape can be similarly measured. Also, when calculating the linear equation,
Instead of the center of gravity shown in the embodiment, information on the two-coordinate maximum point of the line segment information may be used. If you do this,
It becomes possible to suppress the error caused by the length of the line segment and measure the posture with high precision. Further, as a method for calculating the equation of a line segment, it is also possible to use a method other than the least squares method. Further, the pitch of the scanning line, etc. may be determined according to the specifications of the apparatus, and the water-saturated invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of the embodiment device, FIGS. 2(a) to (d) are diagrams showing the concept of attitude measurement processing in the embodiment device, and FIG. This figure shows a correction process for a linear equation, and FIG. 4 is a diagram showing a process control sequence of the embodiment apparatus. DESCRIPTION OF SYMBOLS 1...Laser range finder, 2...Line segment cutting section, 3...Collection importing section, 4...Line generation section, 5.
...Line correction section, a, b, C...Target object, old, h2
．． ~h10...line segment, flj2J3...straight line. Applicant Todoroki Director of the Agency of Industrial Science and Technology Figure 2

Claims (4)

[Claims] (1) Means for sequentially inputting distance information regarding the object to be measured using a light projection means as line information at a predetermined scanning interval, and sequentially extracting information on a line segment indicating the object to be measured from each of the line information. and means for determining the orientation of the object to be measured as a linear equation from the connection relationship between each scanning line of information on each of these line segments. (2) The linear equation calculates a set of line segments that are mutually related between each line from information on the length and position of the line segment of the object to be measured, which is extracted from each line information at a predetermined scanning interval, The posture measuring device according to claim 1, wherein the posture measuring device is calculated as an equation expressing a straight line connecting a set of these line segments. (3) The equation expressing the straight line connecting the set of line segments is successively modified using information on the line segments added to the set of already determined contractions. posture measuring device. (4) The posture measuring device according to claim 1, wherein the light projection means comprises a laser range finder.